This is a request for a Scientist Development Award for Clinicians. The longterm objectives of this grant are to provide a supervised research and educational experience for the applicant that will enable him to become an independent investigator in the neurobiology of childhood neuropsychiatric disorders. Specifically, the award will allow the applicant to extend his use of the recent technological advances in neuroimaging to study CNS structure and function in children with neuropsychiatric disorders, particularly Tourette's syndrome (TS), Obsessive-Compulsive Disorder (OCD), and Attention Deficit Hyperactivity Disorder (ADHD). The award will make possible the continuation of the applicant's research training and career development by providing a full complement of didactic and practical experience in the application of MRI technologies to the study of childhood neuropsychiatric disorders: mentorship with an expert in structural and functional magnetic resonance imaging (MRI); coursework in neuroscience, MR image analysis, computer science, and advanced statistics; collaboration with world-renowned experts in MR and image analysis; visits to neuroimaging laboratories to learn, first hand, state- of-the-art image analytic techniques and activation protocols; and attendance at neuroimaging workshops and conferences. The award will protect the applicant from the clinical and administrative responsibilities that would otherwise interfere with his development into an independent researcher in child psychiatry at this critical point in his academic career. Finally, the award will allow Dr. Peterson to take full advantage of the unique opportunity available to him from his ongoing, large-scale MRI study of the family-genetic and environmental determinants of brain structure and function in TS, OCD, and ADHD; he will have access to an enormous clinical and neuroimaging database, and he will be able to perform additional structural and functional MR studies at minimal cost, which will enable him to apply practically what he learns didactically in the timespan of this award. If given the means to exploit these opportunities, the applicant will be poised to become an expert in the application within clinical populations of the methodologies of functional MRI, which offers every promise of being a neuroimaging modality that can safely image brain function in childhood neuropsychiatric disorders and throughout normal child development.